1. Field of the Invention
Aspects of this invention relate generally to systems for shaping light emission patterns of solid state lighting units or assemblies, and more particularly to systems for shaping the light emitted from Light Emitting Diodes (“LEDs”) used in indoor or outdoor lighting units.
2. Description of Related Art
LEDs are now available in high power packages that provide high lumen output from a single source. In the context of indoor and outdoor lighting, one challenge in connection with the use of such “high-output LEDs” is collecting and reshaping the light to efficiently illuminate the areas and shapes required by industry lighting standards and the application. These high-output devices have a much larger light emitting area that requires attention to optical design. And unlike previous smaller LEDs that generally have integral refractive optics, high-output LEDs have large area wide-angle light emissions that almost always require secondary optics. High-output LEDs are also known to produce considerable heat and so must be mounted to a thermally dissipating structure to ensure maximum life.
The thermal and optical requirements of high-output LEDs require mutual consideration, and while thermally mounted, the optical solution must capture or otherwise use or control light emissions from 360-degrees around the LED's forward hemisphere and redirect the light toward the axis of the desired illumination pattern. A common illumination pattern required of such a lighting unit usually requires that it be mounted midway in a rectangular lighting pattern that requires the most significant percentage of the light from the LEDs to be directed away from the lighting unit. Additionally, for luminous uniformity from streetlight luminaires or parking garage luminaires, for example, the application can require twenty times more light directed toward the far field than the amount of light required directly beneath the luminaire. Applicants note that as used throughout, the term “luminaire” is to be understood broadly as being any complete lighting unit.
Conventional optics of the prior art commonly have a combination of lenses and reflectors to collect the various angles of light emitted from the LED in order to shape its output into appropriate patterns. Refractive designs for wide angles or multiple angles or sharp bending will typically suffer losses due to internal reflections within the refractive lens.
Each LED can require different optical solutions or dedicated optics for each application. For example, one industry standard for a streetlight luminaire requires a lighted swath of about 30-feet by 200-feet with the luminaire mounted 24-feet high near the center of that pattern. Additionally, an interior parking garage luminaire must light a swath of about 20-feet by 70-feet from a ceiling mounted luminaire only 8-feet high. The garage luminaire must also light the walls and ceiling, thus it must have considerably different optics than a streetlight luminaire.
The demand for LEDs of all kinds for illumination has created a multitude of applications, each requiring special optical shaping of the LED light output pattern. It is known that LED manufacturers are getting more light output with phosphor deposition and optical techniques that don't necessarily conform to true Lambertian or standard emission patterns, which can challenge or obsolete existing optics already set by LED integrators. A phenomenon created by some manufacturers with white LEDs occurs with their radial phosphor deposition at the LED chip, thereby producing more than one correlated color temperature (“CCT”) emission in the spatial radiation pattern of the same LED.
Mass production of a molded optical solution, whether the system is optically refractive with an injection-molded lens or reflective with a deposited metalized finish on a molded substrate, requires intricate tooling and a highly polished mold. Such tools, though capable of mass production, are relatively expensive. Alternately, rapid prototyping methods through which a single part may be fabricated, though capable of smaller quantity production, ultimately cost even many times more than that of a mass production part while still requiring polishing. Either process can take several months or more to complete.
Again, each LED illumination product may require dedicated optical solutions for each application. For example, one industry standard for a streetlight luminaire requires a lighted swath of at least 40-feet by 200-feet with the luminaire mounted 24-feet high and situated asymmetrically or off-center of that pattern, or asymmetrical beam shaping. While asymmetrical optics may also be accomplished in molded refractive or reflective parts by adding or removing curvature or angle on a side of the mold, however, this does cause other complications as known in the art: (1) each half of the illumination task of the streetlight requires a different or mirror image mold, likely to require additional financial investment as well, and (2) draft angles and often necessarily symmetrical mold geometry can complicate some asymmetrical parts fabricated with a conventional release mold without special gates or slides, potentially adding further cost and delay to mold fabrication. Furthermore, LED integrators often mix colors of LEDs to affect different CCT, which can be problematic since LED family characteristics vary differently with time and environment.
In the prior art, U.S. patent application Ser. No. 11/085,891 by Applicant Patrick Mullins teaches a technique with a reflector system that uniformly illuminates those areas nearer to the luminaire at luminance levels inversely proportionate to those levels farther away. In U.S. Pat. No. 6,641,284 to Stopa et al., a “linear parabolic” shaped reflector is disclosed having no side lobe reflectors. In U.S. Pat. No. 6,318,886 to Stopa et al., there is disclosed a rectangular array of LEDs, each in a “frustoconical” reflector involving an array of circular light sources that can concentrate the LED light into a group of circular shapes proportionally similar to the shape of the array itself. U.S. Pat. Nos. 4,386,824 to Draper and 6,048,084 to Sedovic et al. disclose a rectangular reflector shape as a means to project light in a spot or flood application. U.S. Pat. No. 6,854,865 to Probst et al. discloses a “deep dish” parabola for a spot effect.
Aspects of the present invention are then directed to one or more features including but not limited to: (1) affixing the LEDs to a heat dissipating structure for proper cooling to maximize LED life; (2) shaping a reflector system into a rectangular or other shape emission pattern to match illumination requirements so as not to waste illumination in circular “spot” patterns; (3) providing a means to align a portion of the LEDs with an appropriate reflector such that segments of maximum candela light rays around the particular portion of the LEDs are captured and amplified or collimated directly to the far field illumination target; (4) capturing the remaining wide angle light from the aligned portion of LEDs to redirect and shape the light into the appropriate illumination pattern; (5) applying an additional portion of LEDs with their own unique optics to light an area beneath the luminaire and light a full area extending between the luminaire and the aforementioned far field; (6) making an illumination unit that is suitably modular such that opposed segments of a required lighting pattern can be illuminated by adjoining opposing modules, and patterns requiring only a segment of illumination can be illuminated by a single lighting module; (7) fabricating an optical reflector system by laser-cutting, water-jet-cutting, die-cutting or other cutting technique of flat metal or poly reflective (greater than 98% reflective) sheeting material to form and shape into a lens reflector, be it rectangular, circular or any other shape; (8) extracting or dissecting the LED angular output to recombine color temperatures and to match illumination requirements of the application; (9) assembling the formed part with tabs or vanes interlocking within slots that are self supporting and locking, utilizing designated tabs to bend or lock and eliminate additional fasteners; and (10) supporting asymmetrical part shaping without the need for relatively costly duplication or reverse molds or the like.
The prior art described above teaches various shaped reflectors formed from various materials and manufacturing methods, but does not teach a reflector system having two-axis control through which beam collimation and wide-angle beam overlapping occur or a method of manufacturing such a system through cutting flat reflective sheeting via laser, water-jet, die, or other such technique to form the resultant flat parts into the three-dimensional reflectors that collect and shape light from solid state LEDs, wherein each axis may be customized by changing only the laser, water-jet, die or other such cutting, bending, or shaping of the flat pieces. Aspects of the present invention fulfill these needs and provide further related advantages as described in the following summary.